Prevalence of sustainable and unsustainable use of wild species inferred from the IUCN Red List of Threatened Species

Abstract Unsustainable exploitation of wild species represents a serious threat to biodiversity and to the livelihoods of local communities and Indigenous peoples. However, managed, sustainable use has the potential to forestall extinctions, aid recovery, and meet human needs. We analyzed species‐level data for 30,923 species from 13 taxonomic groups on the International Union for Conservation of Nature Red List of Threatened Species to investigate patterns of intentional biological resource use. Forty percent of species (10,098 of 25,009 species from 10 data‐sufficient taxonomic groups) were used. The main purposes of use were pets, display animals, horticulture, and human consumption. Intentional use is currently contributing to elevated extinction risk for 28–29% of threatened or near threatened (NT) species (2752–2848 of 9753 species). Intentional use also affected 16% of all species used (1597–1631 of 10,098). However, 72% of used species (7291 of 10,098) were least concern, of which nearly half (3469) also had stable or improving population trends. The remainder were not documented as threatened by biological resource use, including at least 172 threatened or NT species with stable or improving populations. About one‐third of species that had use documented as a threat had no targeted species management actions to directly address this threat. To improve use‐related red‐list data, we suggest small amendments to the relevant classification schemes and required supporting documentation. Our findings on the prevalence of sustainable and unsustainable use, and variation across taxa, can inform international policy making, including the Intergovernmental Science‐Policy Platform on Biodiversity and Ecosystem Services, the Convention on Biological Diversity, and the Convention on International Trade in Endangered Species.

which species groups to include in our analyses. We selected taxonomic groups for inclusion 24 based on the following criteria: >40% of all extant, Data-sufficient species have at least one 25 purpose of use coded (thus selecting taxonomic groups with high prevalence of use); or the 26 proportion of least concern (LC) species with at least one purpose of use falls above or within the 6 range of the proportion of species with use and trade documentation across the other Red List 28 categories (thus also selecting taxonomic groups where use and trade may be relatively low, but 29 use and trade in LC species is coded to a similar level as that of species in other Red List 30 categories). This limited our dataset to the following taxonomic groups which have adequate 31 recording of use and trade: birds, amphibians, selected reptiles, cycads, conifers and selected 32 dicots from the terrestrial group; and corals, selected bony fishes, crustaceans and cone snails 33 from the aquatic species group (Appendix S5). We excluded mammals, cephalopods and 34 cartilaginous fishes as they meet neither criterion, meaning within these groups there is either 35 relatively little use, or Red List documentation of use is incomplete.

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For each taxonomic group, we calculated the total number of species recorded as being used for 38 at least one purpose in the use and trade classification scheme. However, we excluded use for the 39 purpose of establishing ex-situ production (use code 16 [Appendix S3]), other (17), and 40 unknown (18). Ex-situ production involves establishing captive populations for conservation 41 breeding and translocation but also for ranching, farming or propagation purposes. It is not 42 possible to distinguish these purposes without the IUCN assessors voluntarily providing 43 information on harvest from captive and cultivated sources. Only eleven species (six 44 cartilaginous fishes, four bony fishes, and one bird) in our analyses had an unknown use and 45 trade category. We summarized the data as the percentage of species recorded for different types 46 of use on the Red List.

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Additive impact scores: 132 8-9: High impact threat 133 6-7: Medium impact threat 134 3-5: Low impact threat 135 0-2: Negligible or no impact threat 136 137 138 * We excluded past threats which were deemed unlikely to return. Where severity or scope of threat is coded as unknown, we assign each a score of 2 (medium), meaning threats with unknown severity or scope were still analyzed if their timing was coded as future or likely to return. Consequently, for threats where both severity and scope were coded as unknown, our approach was precautionary in assuming the threat was at least medium impact; for threats where one of severity or scope are coded was unknown, and the other either slow or fluctuating, or negligible or low impact, our approach was evidentiary in assuming that the threat was not medium impact. We provide a short-hand summary of the main analyses undertaken in this paper, which 146 correspond to the numbers at the bottom of Table 1.  Threat impact score: A score calculated from a combination of threat scope, severity and timing.

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Threat scope: The scope of the threat, affecting the whole (>90%); majority (50-90%); minority 223 (<50%); or an unknown proportion of the population. This is only optional information to be 224 provided in the Red List assessment.

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Threat severity: The severity of the threat, given as: causing very rapid declines; rapid declines; 226 slow, significant declines; causing/could cause fluctuations; negligible declines; no decline; or 227 unknown. This is only optional information to be provided in the Red List assessment.

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Threat timing: The timing of the threat given as: ongoing; past (unlikely to return); past (likely to 229 return); future; or unknown. This is recommended information to be provided in the Red List  252 * Taxonomic groups included in this study, classed as aquatic for primarily aquatic groups and terrestrial for primarily terrestrial groups. Bony fishes, dicotyledons (dicots), and reptiles include selected higher-level taxa, see Appendix S1 for detailed listing of taxonomic groups. Cephalopods, cartilaginous fishes, and mammals were excluded in analyses based on the use and trade classification scheme due to insufficient data (Appendix S5). † Number of Red List assessments of extant, data-sufficient species published before 2010. ‡ Number of Red List assessments of extant, data-sufficient species published between 2010 and 2019. § Percentage of outdated assessments (published before 2010) formulated from the total numbers of assessments presented in Table 1 columns 1 (All) and 3 (Used). ** Species with adequate use and trade documentation. species with declining population trend; LC(?), least concern species with unknown population 273 trend; LC(*), least concern species with stable or increasing population trend; NT, near Further, it would be useful to better understand and quantify the degree to which species can be 359 subject to some level of use without this resulting in them becoming threatened (i.e., impact is 360 low, highly localized, negligible or no impact). This requires that the effects of BRU be more 361 consistently recorded for LC species (recommendation three). NT and threatened species with some documentation of whether a harvest management plan is in 370 place (as opposed to being left blank). Whether international trade controls are in place is 371 generally better documented than whether a harvest management plan is in place. This is likely 372 because information on whether species are in a CITES Appendix or subject to some other 373 policy controls is easier to obtain than on whether a harvest management plan is in place.

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Finally, the addition of a check-box to indicate when the classification schemes for a given 376 species assessment have been filled in at the recommended level, would be a powerful addition 377 to the Red List documentation (recommendation five).